1. Field of the Invention
The invention relates to computer system chassis design. More particularly, the invention relates to supporting electronic expansion cards mounted to a motherboard.
2. Description of the Related Art
Computer system such as PCs and servers typically include a central or primary circuit board, commonly referred to as a “motherboard,” “baseboard,” or “system board,” providing electrical and logical connections by which components communicate. A motherboard typically includes integrated components, such as processors, drive controllers, video controllers, primary memory, interrupt controllers, and BIOS, as well as electronic connectors for connecting additional components. A component that interfaces with a motherboard connector may take the form of a separate circuit board generally referred to herein as an “electronic card.” An expansion card is an electronic card that removably interfaces with a motherboard to provide additional functionality. Common examples of expansion cards include peripheral component interconnect (PCI) and industry standard architecture (ISA) expansion cards known in the art. An expansion card includes electrical contacts on one edge that fit into the slot of a corresponding “edge connector” on the motherboard, to provide electronic communication between the expansion card and the motherboard. The use of expansion cards and other electronic cards is not limited to PCs and servers, however. Expansion cards may also be found in other types of electronic applications having a primary circuit board, such as in gaming consoles.
Most edge connectors provide some structural and mechanical support to the expansion card along an edge of the expansion card. The edge connector typically provides a friction fit with the expansion card, which helps retain the card on the connector and holds the card in a desired orientation (such as 90 degrees) with respect to the motherboard. An adjacent edge of the expansion card may also be supported by a back wall of the computer chassis. Though the support provided at the edge connector and back wall of the chassis may be sufficient to hold the expansion card in the desired orientation when the chassis is stationary, the unsupported edges can be a source of structural vulnerability. For example, when the chassis is open, the card may be inadvertently bumped at the unsupported edge. Also, movement of the chassis when transporting or installing the chassis can cause undesirable movement of the card under its own inertia. Such impacts or movement can partially unseat the card from its edge connector, causing a loss of electronic communication between the card and connector. If the card is directly impacted, the card or connector may even be damaged. Additional support is, therefore, desired. In particular, heavier PCI cards, and especially video cards and cards with top cabling, need additional support to ensure they remain seated on the motherboard during transportation.
A number of card retention devices are available in the industry for providing supplemental support to expansion cards while connected to a motherboard. However, these devices typically provide such support at a fixed, pre-selected support location along the expansion card. This is a problem because of the multitude of different sizes, designs, and features of cards available. Thus, a number of electronic cards will inevitably be structurally incompatible with currently available card retention devices, such as due to the shape of the card or due to particular features on the card that interfere with a card retention device at the intended support locations. Therefore, there is a need for improved systems to support electronic cards secured to a circuit board. In particular, it would be desirable to have a card retention device that is capable of supporting an electronic card regardless of the variances in shape, size and features among compatible cards.